Endobronchial blockade has been used for single lung ventilation for more than 50 years. An endotracheal tube is positioned within the trachea of a patient. Selective collapse of a targeted lung, or a part thereof, is accomplished by inflating a balloon which is placed on the end of a bronchial blocker protruding from the endotracheal tube thereby restricting airflow to or from the targeted airway.
Use of a single lumen endotracheal tube with a bronchial blocker to allow single lung ventilation soon declined in popularity because it is time consuming and difficult to place the bronchial blocker in position. Moreover, dislodgement of the bronchial blocker is common.
An approach to single lung ventilation described by Inoue et al. (The Journal of Thoracic and Cardiovascular Surgery, Vol. 83, No. 6, pp. 940-41 (1981)) involved the use of an endotracheal tube having a single lumen made of inert silicone. This type of tube, which has come to be called the UNIVENT.TM. tube (manufactured by Fuji Systems Corporation), has been widely used in adults for both pulmonary and non-pulmonary surgical procedures including operations on the esophagus, the mediastinum and on the ascending and descending aorta. Additionally, the UNIVENT.TM. tube is used to provide surgical exposure for procedures via thoracoscopy.
Currently, various types of double lumen endotracheal tubes are available for single lung ventilation. A double lumen tube, as shown in FIG. 3, comprises an endotracheal tube with a divider extending axially through the lumen of the tube thereby dividing the lumen into two separate sections. Examples of these types of endotracheal tubes include the Carlens and Robertshaw tubes (Brit. J. Anaesth., Vol. 34, pp. 576-79 (1962) and Journal of Thoracic Surgery, Vol. 20, pp. 151-57 (1950)). Early versions of these tubes were made of red rubber, however the modern double lumen endotracheal tube is made of polyvinylchloride.
There are various risks and potential complications attendant to the use of double lumen tubes. Such risks and complications include bronchial and tracheal rupture, traumatic laryngitis, mucosal damage and improper positioning of the tube for the procedure to be performed. Additionally, double lumen tubes are frequently contraindicated in patients presenting a difficult airway and in those patients who are presented for emergency surgery with a full stomach. A further disadvantage attendant to use of double lumen tubes is the need to exchange such double lumen tubes for single lumen tubes upon completion of surgery in those patients requiring post-operative mechanical ventilation. This need arises because double lumen tubes increase resistance to airflow through the tube. Further, due to their necessarily smaller inner diameter, double lumen tubes have an increased risk of becoming plugged with secretions and have a high risk of dislodgement from their proper position within the patient's airway.
The foregoing discussion applies to surgery in general and specifically to adult surgery. When similar procedures are to be used with pediatric patients, additional complications can arise. The smaller size of the pediatric patient makes the margin for error in positioning the tube much smaller.
Heretofore, various methods have been used to achieve lung separation in children. A single lumen tube can normally be passed into either the right main bronchus or the left main bronchus of a pediatric patient. With the single lumen tube approach, reinstitution of two lung ventilation is difficult due to the surgical environment which severely restricts the attending physician's access to the patient's airway. With the single tube approach, when the tube is partially withdrawn in the course of attempting to reinitiate dual lung ventilation, there is a serious risk of removing the tube too far whereupon it can be difficult or impossible to reposition the tube to reinitiate dual lung ventilation. Restarting dual lung ventilation should be accomplished prior to closing the incision.
In some cases, intubation in pediatric patients can be accomplished using fiber optic bronchoscopy. Lung separation has been achieved using a single lumen endotracheal tube and a bronchial blocker such as a FOGARTY.TM. embolectomy catheter (available from Baxter International, Inc.), a SWAN-GANZ.TM. catheter (available from Arrow International, Inc.), or a FOLEY.TM. catheter (also available from Baxter). These methods of lung separation are less than ideal because of the difficulty in maneuvering to achieve exact placement of the blocker and the high risk of dislodgement of the blocker from its optimal position. Further, the known double lumen endotracheal tubes are not practical to use with small children since the small size of the child's trachea would require that each lumen of a double lumen pediatric endotracheal tube be exceedingly small, making the tube prone to clogging with secretions and causing a high resistance to gas flow.
U.S. Pat. Nos. 3,599,642; 3,754,554; 3,948,255; 4,022,219; 4,050,466; 4,275,724; 4,329,983; 4,329,984; 4,331,143; 4,502,482; 4,582,762; 4,593,690; 4,622,965; 4,641,646; 4,655,214; 4,685,457; 4,722,335; 4,723,543; 4,727,872; 4,739,756; 4,774,943; 4,825,858; 4,825,861; 4,827,925; 4,840,172; 4,840,173; 4,850,349; 4,865,586; 4,892,095; 4,909,248; 4,955,375; 4,960,122; 4,976,261; 5,005,573; 5,009,227; 5,020,534; 5,033,466; 5,038,777; 5,042,476; 5,054,482; 5,056,514; 5,058,577; 5,060,647; 5,067,497; 5,069,206; 5,076,268; 5,076,269; 5,119,811; 5,143,062; 5,146,913; 5,146,916; 5,174,283; 5,201,310 and 5,203,320 are prior art which may be relevant to the patentability of this invention.
Additional prior art which may be relevant to the patentability of this invention are the articles "Exsanguinating Hemoptysis" by Garzon, Cerruti and Golding appearing in The Journal of Thoracic and Cardiovascular Surgery, Volume 84, pages 829-833, published in 1982; "A New Tube for Single Lung Ventilation" by Karwande, appearing in the October, 1987 issue of the journal Chest at pages 761-763; "The Urinary Catheter as a Bronchial Blocker" by Conacher, appearing in the journal Anaesthesia, Volume 38, pages 475-477, published in 1983; "Airway Management During Anesthesia for Double-Lung Transplantation Using a Single-Lumen Endotracheal Tube with an Enclosed Bronchial Blocker" by Scheller, Kriett, Smith and Jamieson, appearing in the Journal of Cardiothoracic and Vascular Anesthesia, Volume 6, No. 2 published in April of 1992 at pages 204-207; "Lobar Bronchial Blockade in Broncho-Plueral Fistula" by Otruba and Oxorn, published in the Canadian Journal of Anaesthesia, Volume 39, No. 2, pages 176-178, published in 1992 and "Use of Fiber Optic Bronchoscope to Assist Placement of a Fogarty Catheter as a Bronchial Blocker" by Oxorn, published in the Canadian Journal of Anaesthesia, pages 427-428.